<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        .con {
            width: 300px;
            height: 100px;
            background-color: red;
        }

        p {
            width: 100px;
            height: 20px;
            background-color: green;
        }
        .black{
            background-color: black;
        }
    </style>
    <script src="myJquery.js"></script>
    <script src="JqDom.js"></script>
</head>
<body>
<div class="cont">
    <span></span>
    <span></span>
    <span></span>
</div>
<div class="con con1"></div>
<p></p>

<p></p>

<p></p>

<div class="conv"></div>
<div class="conv"></div>
<div class="conv"></div>
<div class="my"></div>
<button>click</button>
</body>
</html>
<script>
 $(".conv").text("<h1>大号字体</h1>")
 console.log($(".conv").text("<h1>大号字体</h1>"));
 console.log($(".conv").text());
</script>